1. Field of the Invention
The present invention relates to a base unit, a spindle motor, and a disk drive apparatus.
2. Description of the Related Art
Hard disk drives typically have spindle motors arranged to rotate disks installed therein. A known hard disk drive and a known spindle motor are described in, for example, JP-A 2006-040423. Paragraph of this publication states that the spindle motor (SPM) is fixed to a base of the hard disk drive (HDD). In addition, paragraph of the publication states that a low-density gas having a density lower than that of air, such as, for example, helium, is used as an atmosphere inside a hard disk assembly (HDA).
A flexible printed circuit board is arranged inside the hard disk drive to supply an electric drive current to a head arranged to perform reading and writing of information from or to a disk. The flexible printed circuit board is connected to an external power supply through a through hole defined in the base. However, a case of the hard disk drive needs to be airtight to keep an interior space thereof clean. Therefore, it is required to seal the aforementioned through hole.
In a known hard disk drive including a base including a through hole, a connector for a flexible printed circuit board is arranged on an upper surface of the base to seal the through hole. However, in the case where an interior of a case is filled with a low-density gas, such as, for example, helium, which tends to easily pass through even a minute gap, as in the case of the hard disk drive described in JP-A 2006-040423, particularly high airtightness is required. Therefore, simply closing the through hole with the connector may fail to prevent a leakage of the low-density gas.
It is conceivable to arrange an adhesive layer between an area surrounding the through hole and the connector, for example, to prevent a leakage of the low-density gas out of the case. In this case, a groove may be defined in the area surrounding the through hole, and an adhesive may be held in this groove. This arrangement contributes to preventing the adhesive from protruding into the through hole or outwardly of the connector, and thus preventing the adhesive from making contact with an electrode terminal of the connector or various electrical wiring arranged around the connector. However, when the connector is fixed to the base through adhesion, a gas bubble may be introduced into the adhesive or the groove, and any gas bubble being introduced might result in a failure to achieve a sufficient adhesive strength and a sufficient sealing area.